1. Field
The present invention relates generally to near field communication and, more particularly, to power saving within such an environment.
2. Description of Related Art
Bluetooth technology is a short-range wireless communications technology to replace the cables connecting electronic devices, allowing a person for example to have a phone conversation via a headset, use a wireless mouse and synchronize information from a mobile phone to a PC, all using the same core system.
The Bluetooth RF transceiver (or physical layer) operates in the unlicensed ISM band centered at 2.4 gigahertz which is the same range of frequencies used by microwaves and Wi-Fi. The core system employs a frequency-hopping transceiver to combat interference and fading.
Bluetooth devices are typically managed using an RF topology known as a “star topology.” A group of devices synchronized in this fashion forms a piconet, which may contain one master and up to seven active slaves, with additional slaves that are not actively participating in the network. Also a given device may also be part of one or more piconets, either as a master or as a slave. In a piconet, the physical radio channel is shared by a group of devices that are synchronized to a common clock and frequency-hopping pattern, with the master device providing the synchronization references. Additionally, Bluetooth devices can be arranged in a peer-to-peer network or mesh configuration as well.
One shortcoming, however, is that in both master and slaver modes, Bluetooth devices frequently open a receive correlation window to detect potential transmissions from a peer device. Detection is accomplished using a relatively long correlation sequence (e.g., 68 bits or 68 μs) even if no device is actively transmitting. Thus, the correlation window is open for the entire period consuming significant amounts of current.